Simple blood-sugar measuring devices have been in practical use for conveniently measuring the blood-sugar level at or away from home.
A blood-sugar measuring device is known wherein an attachment including a biosensor and a lancing needle is mounted to a tip portion of the measuring device for performing concentration measurement with respect to body fluid, as disclosed in JP-A 2000-231 for example. While a fluid feed port of the biosensor is pressed against the skin, the lancing needle of the blood-sugar measuring device is caused to protrude beyond the biosensor into the skin for bleeding. The blood bleeding from the skin is supplied to a reacting portion via a capillary of the biosensor to form a liquid phase reaction system. The blood-sugar measuring device calculates the blood-sugar level based on the value of a response current measured when a voltage is applied across the liquid phase reaction system.
However, the attachment incorporating the biosensor may fail to properly introduce blood via the sample feed port because if the skin contacts the biosensor improperly to create a gap between the biosensor and the skin, the blood may flow out along the biosensor and/or the skin via the gap. As a result, the reacting portion may fail to be supplied with an enough amount of blood needed for proper measurement.
Proposals have been made to solve the above problem by applying a water-repellent coating around the fluid feed port of the biosensor for blood leakage prevention or by arranging the feed port near the reacting portion. However, these countermeasures have turned out still insufficient for preventing blood leakage on lancing.